The invention relates to a collapsible freight container for air transport. Also within the scope of the invention is a process for its manufacture and a method for folding down a freight container according to the invention.
Air-freight containers, for simplicity designated in the following simply as freight container, are necessary for the storage and transportation of freight such as fragile goods and perish-able goods, suitcases etc.
Because of the limited space available for freight in the aircraft the shape of the freight container is often designed to make best possible use of that available space, that is, such that the inner wall of the round aircraft fuselage is taken into account. This way the available loading space can be used very efficiently. For that reason freight containers are often not cube-shaped.
The storage area for empty freight containers in airports is limited. Consequently empty freight containers produce problems concerning their storage in airports. For cost reasons the airline companies do not wish to have large quantities of freight containers stationed world wide. This means, however, that numerous empty freight containers have to be transported between the various airports.
For example it is not always possible onboard an outward flight, to carry sufficient freight containers for use on the return flight. As a result airlines lose out on turnover if they do not have sufficient numbers of freight containers at the airports in question. The same applies if not all of the freight containers carried on the outward flight can be used on the return flight. The fuselages of the various different aircraft are often different in shape or dimen-sions, for which reason not all aircraft are suitable for the return transport of empty freight con-tainers of a particular size and dimension.
Further, in particular when they are very busy, the airlines require an above average number of freight containers. At peak times the airlines must therefore have a corresponding large number of empty containers in store, or they must purchase or lease additional containers at short notice.
Up to now the above mentioned problems have been solved by using one-way containers or freight palettes with only nets to secure the load in place.
The possibility of folding or collapsing freight containers, to reduce the space required to only a fraction of that occupied when in use, overcomes the above mentioned disadvantages. This means that a large number of empty, collapsed freight containers can be housed in little space both for the transportation and for storage purposes.
As already mentioned, freight containers for aircraft are often not cubic in shape, but instead take into account the shape of the freight space inside the fuselage, it is therefore necessary to develop special folding methods.
A common type of freight container of the above mentioned kind is described e.g. in EP 0 313 601. That freight container is a body delimited by straight faces. It comprises a base panel with support frame mounted thereon containing vertical side sections and horizontal roof sections, whereby on one side, the side sections towards the base are inclined into the interior of the container and delimit an inclined lower wall area. In the case of this generally known version one also speaks of a container balcony on the freight container. DE 28 34 175 also describes a freight container with a similar structure.
Because of the above mentioned complicated wall structures, most known foldable freight containers that feature such a balcony are labor intensive and complicated to dismantle and build up again, and often require several helpers to hold and build them up or collapse them. Further, the available foldable freight containers are often constructed on the principle of dismantling into several individual parts and/or separation of frame-sections and elements for the frame or cladding. Furthermore, the foldable freight containers available up to now cannot be reduced to a minimum residual height which is significantly smaller than the length of the projection or vertical height of the side sections inclined inwards towards the base without the container being dismantled into individual parts or areas of frame with a common wall side and common normals being segmented by hinges.
Document EP 0 822 152 describes a collapsible freight container which can be folded together like a accordion on two facing sides each of which is divided into three frames. Hydraulic damping elements ensure that the collapsing of the container takes place in a con-tinuous manner. In that publication certain cladding elements enclosed in frames are freed from the structural frame and laid together separately. This solution suffers from the great disadvantage that the freight container can be folded down only to an overall height which corresponds to the vertical height of the inclined section at the side running towards the base; this means that the container can be folded down at most to a height of 25-30% of its operational height and still takes up a lot of space.
Further the principle of folding, that is the separate fold down of certain wall elements, is complicated and the hydraulic damping elements are intensive in maintenance.
Accordingly, it is the object of the present invention to provide a collapsible freight container for air transport which can be collapsed within a short space of time with little manipulation and with little or no tools or aids and can likewise be rebuilt with little manipulation and with little or no tools or aids, whereby the container does not have to be separated into individual parts on collapsing it.